When patients are evaluated only once under treatment, then the presence of dropouts makes it hard to comply with the intention-to-treat (ITT) principle. However, when repeated measurements are taken then one can make use of the observed portion of the data to retrieve information on dropouts. Generally, commonly used methods to analyse incomplete longitudinal clinical trial data include complete-case (CC) analysis and an analysis using the last observation carried forward (LOCF). However, these methods rest on strong and unverifiable assumptions about the dropout mechanism. Over the last decades, a number of longitudinal data analysis methods have been suggested, providing a valid estimate for, e.g., the treatment effect under less restrictive assumptions.

The assumptions regarding the dropout mechanism have been classified by Rubin and co-workers as: missing completely at random (MCAR), missing at random (MAR) and missing not at random (MNAR). We will review various repeated measurements models and indicate under which missing data mechanism they will provide valid estimates of the treatment effect. Finally, since it is impossible to verify that the dropout mechanism is MAR we argue that, to evaluate the robustness of the conclusion, a sensitivity analysis thereby varying the assumption on the dropout mechanism should become a standard procedure when analyzing the results of a clinical trial.

Objectives

Gain insight in various repeated measurements models and under which missing data mechanism they will provide valid estimates of the treatment effect.

Assessment

Attendance, Assignment(s)

Reduction on fees

PLEASE NOTE THIS DOES NOT APPLY TO THE RESEARCH MASTERS (120 ECTS)

50% reduction on our fees for participating institutes of NIHES

This 50% reduction is offered to participants appointed at the departments or sections participating in NIHES.

University Medical Center Rotterdam/Erasmus University Rotterdam:

Department of Epidemiology

Department of Public Health

Department of Psychiatry, Section of Medical Psychology and Psychotherapy

Department of Child and Adolescent Psychiatry/Psychology

Department of Health Policy and Management

Department of Medical Informatics

Department of General Practice

50% reduction on our fees for NIHES affiliated partners

This 50% reduction is offered to participants appointed at the following NIHES affiliated partners: